Today I had a university oral exam.
I didn't do very well, but I didn't do too badly either.
When the time came, the professor let me choose whether to pass with a low grade or make me come back the next time.
It was really better for me to pass regardless of the grade, but being the faggot that I am, I told the professor to decide.
He reiterated TWICE that it was my decision, I denied it, he made up his mind, and decided I'd go next time.
Now I'm going home full of regret like a faggot.

What exactly went wrong here? Lack of assertiveness, right?
How do I even train it?
Any similar experiences?